2026 ICD-10-CM Diagnosis Code T88.3XXSMalignant hyperthermia due to anesthesia, sequela

ICD-10-CM Codes›S00–T88›T80-T88›T88

ICD-10-CM T88.3XXS
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

T88.3XXS is a billable ICD-10-CM diagnosis code for malignant hyperthermia due to anesthesia, sequela. The 7th character S marks it as a sequela code, which reports a problem that remains after the original condition has resolved. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 922 through 923. The code is exempt from POA reporting. Coders also document this condition as drug-induced hyperpyrexia. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Complication, sequela.

Code Identity

ICD-10-CM Code
T88.3XXS
Billable Status
Yes — Valid for Submission
Code Describes
Malignant hyperthermia due to anesthesia, sequela
Short Description
Malignant hyperthermia due to anesthesia, sequela
Same as the full description in the CMS dataset.
Parent Code
T88.3
Malignant hyperthermia due to anesthesia

Code Classification

ChapterS00–T88Injury, poisoning and certain other consequences of external causes
SectionT80-T88Complications of surgical and medical care, not elsewhere classified
CategoryT88Other complications of surgical and medical care, not elsewhere classified
This CodeT88.3XXSMalignant hyperthermia due to anesthesia, sequela

Present on Admission (POA)Billing

T88.3XXS is exempt from POA reporting on inpatient claims to general acute care hospitals. Review other POA exempt codes.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Drug-induced hyperpyrexia
  • Hyperpyrexia
  • Malignant hyperthermia
  • Malignant hyperthermia caused by anesthetic

Coding GuidelinesGuidance

The appropriate 7th character is to be added to each code from block Other complications of surgical and medical care, not elsewhere classified (T88). Use the following options for the applicable episode of care:

  • A - initial encounter
  • D - subsequent encounter
  • S - sequela

Source: ICD-10-CM Official Guidelines for Coding and Reporting, FY 2026, published by CMS and the National Center for Health Statistics.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR INJ076
Complication, sequela
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Malignant Hyperthermia

    rapid and excessive rise of temperature accompanied by muscular rigidity following general anesthesia.

  • Hyperpyrexia

    body temperature of 106 degrees fahrenheit (41.1 degrees celsius) or higher.

  • Malignant Hyperthermia Syndrome|Malignant Hyperpyrexia|Malignant Hyperthermia|Malignant Hyperthermia

    a rare disorder characterized by rapid rise of the body temperature, accompanied by rhabdomyolysis and, if untreated, by collapse and death. it occurs in susceptible individuals who receive certain drugs for general anesthesia, gas anesthetics, or succinylcholine. it may be inherited in an autosomal dominant pattern.

Patient EducationClinical

Anesthesia

Anesthesia is the use of medicines, called anesthetics, to prevent pain during surgery and other medical procedures. Medicine may be given by injection, inhalation, topical lotion, spray, eye drops, or a skin patch.

The full article covers:

  • What is anesthesia?
  • What is anesthesia used for?
  • What are the types of anesthesia?
  • What are the risks of anesthesia?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert T88.3XXS to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
909.3 Late eff surg/med compl
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About T88.3XXSOverview

Is T88.3XXS (Malignant hyperthermia due to anesthesia) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report malignant hyperthermia due to anesthesia, sequela on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What does the 7th character S in T88.3XXS mean?

The final character S makes this a sequela code: it reports a lingering problem that remains after the malignant hyperthermia due to anesthesia itself has resolved, not the original event.

What MS-DRG does T88.3XXS group to?

When malignant hyperthermia due to anesthesia, sequela is the principal diagnosis on an inpatient stay, it groups to MS-DRG 922, 923, with relative weights from 1.0177 to 1.7494 depending on complications. Higher weights mean higher Medicare reimbursement.

Is T88.3XXS exempt from POA reporting?

Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for malignant hyperthermia due to anesthesia, sequela on inpatient claims.

What is the ICD-9 equivalent of T88.3XXS?

Under the General Equivalence Mappings, malignant hyperthermia due to anesthesia, sequela converts to ICD-9-CM 909.3 (late eff surg/med compl). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.